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M&R > The Resting Membrane Potential > Flashcards

The Resting Membrane Potential Flashcards

0
Q

How is the RMP expressed?

A

The voltage inside relative to the outside

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1
Q

What is a membrane potential?

A

An electrical potential difference across a cell’s plasma membrane

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2
Q

What is the RMP range for a nerve cell?

A

-50 - -90mV

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3
Q

What is the main ion involved in setting up the RMP?

A

K+

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4
Q

When potassium channels are open, in which direction does potassium move?

A

Out of the cell, down its concentration gradient

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5
Q

What are the intracellular and extracellular concentrations of potassium?

A

Intracellular: 160mM
Extracellular: 4.5mM

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6
Q

What does the Nernst equation calculate?

A

The equilibrium potential of an ion

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7
Q

How is the equilibrium potential of potassium (Ek) reached in a resting cell membrane? (Imagine there are no other ions involved)

A

Potassium channels are open so potassium diffuses out down its concentration gradient
This makes the cell negative and this opposes outflow of K+
Some potassium moves back in until an equilibrium is reached (Ek)
This potential difference is the the Ek

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8
Q

Is the resting membrane potential more or less negative than Ek?

A

Less negative

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9
Q

What effect does increasing the concentration of potassium extracellulary have on the RMP?

A

Makes it more positive

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10
Q

Define depolarisation

A

Decease in membrane potential so that inside the cell becomes less negative

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11
Q

Define hyperpolarisation

A

An increase in membrane potential so that inside the cell becomes more negative.

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12
Q

Which ions have a positive equilibrium potential and which have a negative one?

A

Positive: Na and Ca
Negative: K and Cl

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13
Q

Opening Na or Ca will hyperpolarise or depolarise the RMP?

A

Depolarise

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14
Q

What is mechanical gating?

A

When an ion channel opens/closes in response to membrane deformation

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15
Q

What can the membrane potential be measured by?

A

A microelectrode

16
Q

What can the resting potential of an animal cell be in the range of?

A

-20 to -90mV

17
Q

What can the resting potential of a cardiac/muscle cell be in the range of?

A

-80 to -90mV

18
Q

How does increasing the permeability of an ion affect the RMP?

A

It moves it closer to the equilibrium potential of that ion

19
Q

What is the equilibrium potential of an ion?

A

The membrane potential at which there is no net movement of the ion across the membrane

20
Q

What is the difference between fast and slow synaptic transmission?

A

Fast synaptic transmission - the receptor protein is also an ion channel. The binding of the transmitter causes the channel to open.

Slow synaptic transmission - the receptor protein and ion channel are separate proteins. May be linked by G proteins or intracellular messengers

21
Q

Name some transmitters at excitatory synapses

A

Acetylcholine

Glutamate

22
Q

Name some neurotransmitters at inhibitory synopses

A

Glycine

γ-aminobutyric acid (GABA)

23
Q

What do excitatory synapses cause?

A

Membrane depolarisation

An excitatory post synaptic potential (EPSP)

24
Q

What do inhibitory synapses cause?

A

Hyperpolarisation

Inhibitory post synaptic potential

25
Q

Which protein is the most important in allowing ionic movement to establish RMP?

A

Voltage-insensitive potassium channels

26
Q

In hyperkalaemia, does the RMP become more positive or negative?

A

Positive

27
Q

In hyperkalaemia, is it harder or easier for an action potential to be fired?

A

Easier because the RMP is closer to the threshold

28
Q

Activation of the glycine receptor results in membrane hyperpolarisation or depolarisation?

A

Hyperpolarisation

29
Q

Which ion is the glycine receptor permeable to?

A

Chloride

30
Q

Inhibitory postsynaptic potentials may be elicited by opening channels for which ions?

A

Potassium and chloride

31
Q

Excitatory postsynaptic potentials may be elicited by opening channels for which ions?

A

Sodium and calcium

M&R (10 decks)

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